1. Field of the Invention
The present invention relates to a gas generator used in a restraining device in a vehicle and the like such as an air bag device, and more particularly to a gas generator used in an air bag system for deploying an air bag in the lateral side of an occupant.
2. Description of Related Arts
A gas generator used in a device that deploys the air bag in the lateral side of the occupant is often formed in an elongated cylindrical shape because of the place where the gas generator is attached. A cylindrical housing is disposed inside a vehicle in the substantially vertical direction or the horizontal direction.
US-A, No. 2008/0078486 discloses the gas generator in which an initiator 32 is disposed at one end portion of an elongated outer housing 12 and a diffuser portion formed with a gas discharge port 20 is provided in an opposite end portion.
In this gas generator, a booster cup 23 storing a booster agent 24 and a divider 28 formed with an opening 28a are disposed in the vicinity of the initiator 32. A gas generating agent 16 is disposed in a space formed by an inner housing 14. A tubular gas passage is formed between the outer housing 12 and the inner housing 14.
The booster 24 burned by the initiator 32 generates combustion products that enter the interior of the inner housing 14 through the opening 28a and burn the gas generating agent 16. Gas generated from the gas generating agent 16 passes through an orifice 18 in the inner housing 14 and escapes through a tubular gap between the outer housing 12 and the inner housing 14 to be discharged from the gas discharge port 20 in the diffuser portion. Parts such as the inner housing 14 realize a formation in which gas flows in a zig-zag pattern, and a conventional filter is not used.
When the gas generator is installed horizontally as illustrated in FIG. 1 of US-A No. 2008/0078486, vibration and the like applied over time to the gas generator installed in a vehicle may cause the gas generating agent 16 to become biased toward a lower side, as shown in the drawing, in a combustion chamber inside the inner housing 14 and may lead to a formation of a gap at an upper side. This tendency increases when, in particular, the gas generating agent 16 disposed in the combustion chamber is not sufficiently held.
When such a gap is created, the combustion products generated by the booster ignites only a part of the gas generating agent 16 and the remainder of the combustion products flows through the gap to the side of the diffuser. In addition, combustion gas generated from the gas generating agent also flows through the gap towards the diffuser portion without igniting the unburned gas generating agent 16 existing in the combustion chamber. Therefore, a sufficient ability to ignite the gas generating agent 16 cannot be secured, leaving room for improvement.